Definition and Classification. When the Prophet sent Muadh to Yemen, he asked him about the sources on which he would base his judgments and approved of his intention of “putting all his energy into formulating his own judgment” in cases where he could find no guidance in the Qur’an and the Sunna. This personal effort undertaken by the jurist in order to understand the source and deduce the rules or, in the absence of a clear textual guidance, formulate independent judgments is what is called ijtihad in the field of Islamic law and jurisprudence. Hashim Kamali proposes the following definition: “Ijtihad is defined as the total expenditure of effort made by a jurist in order to infer, with a degree of probability, the rules of Sharia from their detailed evidence in the sources. Some ulama have defined ijtihad as the application by a jurist of all his faculties either in inferring the rules of Sharia from their sources or in implementing such rules and applying them to particular issues. Ijtihad essentially consists of an inference [istinbat] that amounts to a probability [zann], thereby excluding the extraction of a ruling from a clear text.”
Like al-maslaha, the legal instrument of ijtihad has been used to justify all kinds of new judgments. So Hashim Kamali quite rightly recalls the general principle (about which the ulama are unanimous), according to which there can be no ijtihad when an explicit text exists in the sources (la ijtihada maa al-nass). This means that if there is an explicit Qur’anic verse whose meaning is obvious and leaves no room for any hypothesis or interpretation (qati al-dalala), no ijtihad is possible. Similarly, if the jurist finds an authenticated hadith (mutawatir, qati al-thubut) whose content is also completely explicit and unambiguous (qati al-dalala), he must use that as his reference and there is no room for the exercise of ijtihad.
Indeed, clear texts that are both authenticated and explicit, even though they are not very numerous, constitute the unalterable foundation, the fixed principles, on which the Sharia is based—principles to which the jurist must refer, from which he must analyze, comment on, and explain texts that contain some conjecture (zanni), and on the basis of which he should also formulate new judgments through a dynamic process when his community faces new situations. The laws and judgments provided by these clear texts together constitute a specific corpus, which the ulama al-usul call al-malum min al-din bil-darura, which means that they bring out the fundamental essence of Islamic law and that to reject them leads to the negation of Islam (kufr).
But the great majority of the verses in the Qur’an and the traditions of the Prophet are not of both a strict and compelling nature. The Qur’an is authenticated in itself (qati al-thubut, of indisputable origin), but most of the verses containing legal judgments (ayat al-ahkam) are open to analysis, commentary, and interpretation (zann¯ı al-dalala), and this is also the case with the ahadith, most of which leave some scope for speculation as much concerning their authenticity (thubut) as concerning their meaning (dalala). This means that the fuqaha (jurists) had, and still have, an important and essential function in the formulation of laws that may be called Islamic. They fulfill this function particularly through their ijtihad, applied at various levels: to understand a specific text (in the light of the whole Islamic legal corpus); to classify texts on the basis of their clarity or their nature (e.g., qati [indisputable] or zanni [conjectural]; zahir [obvious] or nass [explicit]; khass [specific] or amm [general]); or to formulate judgments where no text exists. Ijtihad taken as a whole (as both source and legal instrument) has in fact been considered by numerous ulama as the third principal source of Sharia, encompassing al-ijma (ijtihad jamai) al-istislah and al-istihsan, as well as other subdivisions recognized among what are called the supplementary sources of the Sharia. As Muhammad Hashim Kamali has emphasized: “The various sources of Islamic law that feature next to the Qur’an and Sunnah are all manifestations of ijtihad, albeit with differences that are largely procedural in character. In this way, consensus of opinion, analogy, juristic preference, considerations of public interest [maslahah], etc., are all interrelated not only under the mean heading of ijtihad, but via the Qur’an and the Sunnah.”
Al-Ghazali, al-Shatibi, Ibn al-Qayyim al-Jawziyya, and, more recently, al-Khallaf and Abu Zahra have referred to this type of classification, underlining the importance of ijtihad as the third source of Islamic jurisprudence, for ijtihad includes all the instruments used to form judgments through human reasoning and personal effort. Ijtihad is, in fact, the rational elaboration of laws either on the basis of the sources or formulated in the light of them. Thus, even ijma (consensus) is the product of a collective human, rational discussion, and so one can conceive—even if it would be very unlikely and rare—that a legal decision made by ijma might eventually become unsuitable and be referred again for debate. As Professor Hamidullah has said in connection with the Hanafi school of law: “The opinion of a jurist can, however, be rejected by another jurist who can offer his own opinion instead. This applies not only to individual opinion or an inference but also covers collective opinion. At least the Hanafi school of law accepts that a new consensus can cancel an old consensus. Suppose there is a consensus on a certain issue. We accept its authority, but it does not mean that no one can oppose it till eternity. If someone has the courage to oppose it with due respect and reason, and if he can persuade the jurist to accept his point of view, a new consensus comes into being. The new consensus abrogates the old one. This principle has been propounded by the famous Hanafi jurist Abu al-Yusr al-Bazdawi in his book Usul alFiqh [Principles of Jurisprudence]. Al-Bazdawi belongs to the fourth and fifth century of the Hijrah. This work is a great contribution to Islamic jurisprudence. It is on account of his statement that we can say that consensus cannot become a source of difficulty for us. If a consensus is reached on some issue and it is found subsequently to be unsuitable the possibility remains that we may change it through reasoning and create a new one canceling the old consensus.”
This analysis recalls an important principle from the realm of usul alfiqh, which is that the Qur’an and the Sunna are the only two indisputable sources, sources at whose core the prescriptive verses and ahadith (ayat waahadith al-ahkam) are divided into two main levels: the qati (indisputable), which is clear in itself, and the zanni (conjectural, open to hypotheses and interpretations), which requires on the part of the ulama an attentive study of the texts in question before they can deduce appropriate judgments on passages taken from the sources. The aim of this type of ijtihad (applied to zanni texts)—sometimes called bayani (explanatory ijtihad)—is to analyze the text (nass) in order to draw from it a ruling and its illa (the effective cause of this specific ruling); this allows both an adequate understanding of the text and consequent analogical reasoning (qiyas) in the light of the historical context. This type of ijtihad has given rise to numerous and diverse subdivisions following the various opinions of the ulama.
There is another type of ijtihad that is applied when there is no scriptural reference. Here, too, we find numerous subdivisions because of the diversity of opinion among the ulama and the collections of writings and commentaries that have been made in the course of history. At least three types stand out:
- Ijtihad qiyasi works by analogical reasoning, taking into consideration the effective cause (illa) of a ruling drawn from the sources.
- Ijtihad zanni comes in when it is impossible to refer to an effective cause; this type is often linked with ijtihad istislahi.
- Ijtihad istislahi is based on al-maslaha and seeks to deduce rulings in the light of the general objective of the Sharia
But the ulama are not unanimous about the specific classification of ijtihad, because they do not even agree on its definition and methods of application.
Another distinction has to do with the degree of ijtihad, which may be absolute (mutlaq) or limited (muqayyad). The first type, also called ijtihad fi al-shar, is based on the ability of the mujtahid (a scholar qualified to practice ijtihad) to extrapolate and formulate his own judgments on the basis of a direct study of the sources. The second, also called ijtihad madhhabi (pertaining to a school), is, by contrast, limited to a particular school of law and the mujtahid must formulate his judgments according to the rules of a given juridical school.